[OT?] TLD auto-discovery in JSP XML syntax?

My web.xml version is 2.4 and i'm using the 1.1.2 versions of jstl and 
standard JARs in my project. I should note that those JARs are in 
EAR/APP-INF/lib and the WAR classloader is prompted to them by the WAR 
manifest (not sure if this is needed. My JSP root elem is as follows:


<jsp:root version="2.0" xmlns:c="http://java.sun.com/jsp/jstl/core"
xmlns:jsp="http://java.sun.com/JSP/Page">

However, c:foo tags are not evaluated at all by the container (tomcat 
5.ish in jboss 4.0.3) and are passed to the output stream as-is.

I tried to figure out what JSR specifies how auto-discovery works  but 
failed miserably. Can someone point out what i'm missing?

Thanks in advance,

Manos